[python] Add logic to clear output folder (#3239)

* add test case

* Update dependencies

* Add changelog .chronus/changes/auto-microsoft-clear-output-dir-python-2025-9-11-13-42-52.md

* Update dependencies (2025-10-11 08:34:33)

* Regenerate for typespec-python (2025-10-11 08:39:41)

* fix regeneration

* fix test case

* fix test case

* Update dependencies

* Update dependencies (2025-10-29 06:18:24)

* update dependency

* add changelgo

---------

Co-authored-by: AutoPrFromHttpClientPython <AutoPrFromHttpClientPython>

Author: msyyc

.chronus/changes/auto-microsoft-clear-output-dir-python-2025-9-11-13-42-52.md

@@ -0,0 +1,8 @@
+---
+changeKind: feature
+packages:
+  - "@autorest/python"
+  - "@azure-tools/typespec-python"
+---
+
+Add logic to clear output folder

.chronus/changes/auto-microsoft-clear-output-dir-python-2025-9-30-2-33-3.md

@@ -0,0 +1,8 @@
+---
+changeKind: internal
+packages:
+  - "@autorest/python"
+  - "@azure-tools/typespec-python"
+---
+
+Exclude unnecessary files from pylint checks to improve execution speed

packages/autorest.python/package.json

@@ -29,7 +29,7 @@
   },
   "homepage": "https://github.com/Azure/autorest.python/blob/main/README.md",
   "dependencies": {
-    "@typespec/http-client-python": "~0.19.2",
+    "@typespec/http-client-python": "https://artprodcus3.artifacts.visualstudio.com/A0fb41ef4-5012-48a9-bf39-4ee3de03ee35/29ec6040-b234-4e31-b139-33dc4287b756/_apis/artifact/cGlwZWxpbmVhcnRpZmFjdDovL2F6dXJlLXNkay9wcm9qZWN0SWQvMjllYzYwNDAtYjIzNC00ZTMxLWIxMzktMzNkYzQyODdiNzU2L2J1aWxkSWQvNTUxNTI4Ny9hcnRpZmFjdE5hbWUvYnVpbGRfYXJ0aWZhY3RzX3B5dGhvbg2/content?format=file&subPath=%2Fpackages%2Ftypespec-http-client-python-0.19.2.tgz",
     "@autorest/system-requirements": "~1.0.2",
     "fs-extra": "~11.2.0",
     "tsx": "~4.19.1"

packages/typespec-python/package.json

@@ -67,7 +67,7 @@
     "js-yaml": "~4.1.0",
     "semver": "~7.6.2",
     "tsx": "~4.19.1",
-    "@typespec/http-client-python": "~0.19.2",
+    "@typespec/http-client-python": "https://artprodcus3.artifacts.visualstudio.com/A0fb41ef4-5012-48a9-bf39-4ee3de03ee35/29ec6040-b234-4e31-b139-33dc4287b756/_apis/artifact/cGlwZWxpbmVhcnRpZmFjdDovL2F6dXJlLXNkay9wcm9qZWN0SWQvMjllYzYwNDAtYjIzNC00ZTMxLWIxMzktMzNkYzQyODdiNzU2L2J1aWxkSWQvNTUxNTI4Ny9hcnRpZmFjdE5hbWUvYnVpbGRfYXJ0aWZhY3RzX3B5dGhvbg2/content?format=file&subPath=%2Fpackages%2Ftypespec-http-client-python-0.19.2.tgz",
     "fs-extra": "~11.2.0"
   },
   "devDependencies": {

packages/typespec-python/scripts/eng/regenerate.ts

@@ -431,11 +431,45 @@ async function runTaskPool(tasks: Array<() => Promise<void>>, poolLimit: number)
     await Promise.all(workers);
 }
 
+// create some files before regeneration. After regeneration, these files should be deleted and we will test it
+// in test case
+async function preprocess(flags: RegenerateFlagsInput): Promise<void> {
+    if (flags.flavor === "azure") {
+        const generalParts = [PLUGIN_DIR, "test", "azure", "generated"];
+        await promises.writeFile(
+            join(
+                ...generalParts,
+                "authentication-api-key",
+                "authentication",
+                "apikey",
+                "_operations",
+                "to_be_deleted.py",
+            ),
+            "# This file is to be deleted after regeneration",
+        );
+
+        const folderParts = [...generalParts, "generation-subdir"];
+        await promises.writeFile(
+            join(...folderParts, "generation", "subdir", "_generated", "to_be_deleted.py"),
+            "# This file is to be deleted after regeneration",
+        );
+        await promises.writeFile(
+            join(...folderParts, "generated_tests", "to_be_deleted.py"),
+            "# This file is to be kept after regeneration",
+        );
+        await promises.writeFile(
+            join(...folderParts, "generation", "subdir", "to_be_kept.py"),
+            "# This file is to be kept after regeneration",
+        );
+    }
+}
+
 async function regenerate(flags: RegenerateFlagsInput): Promise<void> {
     if (flags.flavor === undefined) {
         await regenerate({ ...flags, flavor: "azure" });
         await regenerate({ ...flags, flavor: "unbranded" });
     } else {
+        await preprocess(flags);
         const flagsResolved = { debug: false, flavor: flags.flavor, ...flags };
         const subdirectoriesForAzure = await getSubdirectories(AZURE_HTTP_SPECS, flagsResolved);
         const subdirectoriesForNonAzure = await getSubdirectories(HTTP_SPECS, flagsResolved);

packages/typespec-python/test/azure/generated/azure-payload-pageable/specs/azure/payload/pageable/_validation.py

@@ -0,0 +1 @@
+# This file is to be kept after regeneration